1. Field of Invention
The present invention relates to a method and a system for estimating State of Health (SOH) of a battery set. More particularly, the present invention relates to a method and a system for estimating SOH without building a data base.
2. Description of Related Art
With the trends of environmental protection and energy saving, hybrid technologies related to the Hybrid Power Vehicles (HPVs) develop. HPVs use gaseous fuels or electricity to assist or replace the liquid fuels as the power source of the vehicles; currently, the types of the HPVs include petroleum-hybrid electric driven, pneumatic-hybrid electric driven or electricity driven.
The Petroleum-Hybrid Electric Vehicles (PHEVs) have the advantages of reducing the fuel consumption, and the difference between a PHEV and an ordinary vehicles is that the PHEV have an additional electric motor and additional rechargeable batteries; when the electric motor is driven, a part of the power would be used to drive the tires and a part of the power would be used to charge the rechargeable batteries by a generator for operating the PHEV.
Therefore, how to effectively control the rechargeable batteries and to promote the performance of the rechargeable batteries is currently the research focus of the PHEVs and the electric vehicles (EVs); wherein the Battery Management System (BMS) is the main line within it. The function of the BMS is to estimate the State of Charge (SOC) and the SOH of the rechargeable batteries, for the users to estimate the recharge time, the mileage and the battery life.
However, the conventional manners of the BMS mainly include the open circuit voltage method, the coulomb counting method (i.e., (current) integration method) and the load voltage method, but the abovementioned manners require much time to establish the measurement data base of the rechargeable batteries for estimating the SOC and the SOH of the rechargeable batteries. In addition, the open circuit voltage measurement of the BMS can only be measured when the rechargeable batteries stop charging and discharging, which is very inconvenient for the users.